Electronic navigation systems implemented in automotive vehicles alleviate operators or passengers of the vehicles from the task of finding the best route to a destination. Such systems are particularly useful in regions unfamiliar to the operator, in that they allow for the avoidance of the tedious task of map interpretation. However, modern navigation systems in vehicles supply a considerable amount of information to vehicle operators. This information needs to be organized and displayed for quick access by the vehicle operator without overly distracting the operator's attention from the vehicle's path. Displaying information without distracting the operator's attention from the road applies in particular to navigation systems that indicate routes on a separate screen. Vehicle operators tend to focus their attention continually on the route mapped on the navigation system's screen, as opposed to the traffic conditions, with obvious risks in terms of safety. To monitor the screen, the operator typically has to look away from the road, and switching back and forth between the road and screen takes time for the operator's eyes to adapt to different focal lengths.
Heads-up displays have become increasingly popular in vehicle navigation and information systems. In heads-up displays, an electronic image of the route information is projected onto the front glass (windshield) of the vehicle so the operator can read the projected information without looking away from the road. When observing the road through the windshield, unacceptable distortion of the projected images may be introduced as a result of the front glass having an extensive surface area and highly complex curved shape. Moreover, in normal driving conditions, the operator's head and eyes are subject to continual vertical and longitudinal bobbing movements induced by vibration of the car. The operator's eyes must thus constantly keep track of the position of the image projected onto the windshield, which makes monitoring of the image exhausting. This can also be confusing and frustrating, particularly when the operator must discern many similar and closely located alternatives, such as closely located driveways, complex intersections with intertwined traffic lanes, complex highway exits, etc.
In systems that display two-dimensional navigation objects such as arrows or simplified maps on the front glass, it is undesirable for such images to be presented in such a way that they appear in the operator's primary area of sight. By “operator's primary area of sight”, a section of a three-dimensional space is meant that encloses the visible road ahead of the vehicle, as well as all the visible objects that are on or relatively close to the road. At the very least, such an image may be distracting or annoying to the operator. Moreover, objects presented in the operator's primary area of sight may obstruct real-world objects on the designated path that the operator needs to pay attention to in the course of normal and safe driving (for example, other vehicles, pedestrians, traffic lights and road signs).